This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2001-290113, filed on Sep. 21, 2001: the entire contents of which are incorporated herein by reference.
The present invention relates to a switchback device and switchback method for inverting the conveying direction of a paper-like material and inverting the top and bottom of the paper-like material.
Conventionally, as a switchback device for inverting the conveying direction of a paper-like material and inverting the top and bottom of the paper-like material, a switchback device of a type of allowing the end of a paper-like material in the conveying direction to collide with a stopper, stopping the conveying of the paper-like material once, sending the paper-like material with the back end thereof positioned ahead in the opposite direction, thereby inverting the conveying direction of the paper-like material is known.
However, in a switchback device of this kind, a paper-like material is stopped by letting the end thereof collide with a stopper, so that a paper-like material comparatively unstiff is bent, thus a jam may occur.
Further, when a switchback device of this kind is applied to a device for continuously conveying a plurality of kinds of paper-like materials different in the length in the conveying direction in a coexisting state, even if the paper-like materials are sent to the switchback device at a constant conveying pitch, a problem arises that the conveying pitch of the paper-like materials after inversion of the top and bottom is not always constant.
Furthermore, when a plurality of paper-like materials continuously sent at a constant conveying pitch are to be continuously switched back, if the conveying pitch between two paper-like materials to be continuously sent is lower than the reference value, a problem arises that the preceding paper-like material collides with the succeeding paper-like material in the switchback device and a paper jam occurs.
The present invention is intended to provide a switchback device and switchback method for inverting paper-like materials stably and surely and keeping the conveying pitch between paper-like materials after inversion constant.
According to the present invention, a switchback device is provided and the device comprises a conveying path to continuously convey a plurality of paper-like materials; a switchback portion to receive the paper-like material conveyed on the conveying path in a nip, clamping the paper-like material, decelerate and stop the paper-like material in the clamping state, then accelerate in an opposite direction, send onto the conveying path, thereby invert a conveying direction of the paper-like material; and a controller to keep the paper-like material stopped in the switchback portion for a time decided depending on a length of the paper-like material to be conveyed to the switchback portion in the conveying direction and control an inversion operation for the paper-like material by the switchback portion so as to send out all paper-like materials from the switchback portion at a same conveying pitch as that before inversion.
Further, according to the present invention, a switchback method is provided and the method comprises continuously conveying a plurality of paper-like materials along a conveying path; receiving the paper-like material conveyed on the conveying path in a nip; clamping the paper-like material in the nip; decelerating and stopping the paper-like material in the clamping state; accelerating the paper-like material in an opposite direction; sending the paper-like material onto the conveying path, thereby invert a conveying direction of the paper-like material; keeping the paper-like material stopped for a time decided depending on a length of the paper-like material to be conveyed in the conveying direction; and controlling an inversion operation for the paper-like material so as to send out all paper-like materials at a same conveying pitch as that before inversion.